Potassium Iodide Instead of Potassium Bromide

Hello PUGers.

I need to mix a developer, with the recipe calling for 1 gram Pot. bromide. I do not have Bromide. I have pot. iodide. If I were instead using iodide, how much iodide would I need? I understand I would need very little, but how much?

Thanks.

Hi, according to Anchell's "The Darkroom Cookbook" sec. ed. 1/10 to 1/100. I have read, but I can't remember where, that when Bromide is substituted by Iodide the image tone gets cooler. I think that you can start with 1/50th and if the image is not too cool for your taste to rise the amount to 1/10th or to desired tone. I just ordered some Pot. Iodide to replace the Pot. Bromide because I found that on the particular paper I'm using right now (Adox Fine Print Vario FB / Efke Varicon) the Bromide gives an unpleasant warmish tone when dry. I tried first to use Benzotriazol instead of Bromide and the results where better, but if I can get even cooler images without using Amidol or some kind of toning (Gold, Iron) will be best!
Anyway, I wish you luck!

Andy

You'd probably be better adding nothing rather than Potassium Iodide.

Ian

Why Ian?

Ian Grant said:

You'd probably be better adding nothing rather
than Potassium Iodide. Ian

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Although I've not kept exact records, testing
paper developers with no bromide included
has lead me to conclude that some papers
do not need a bromided developer. Also,
some may need more than others. Dan

Potassium Iodide can completely inhibit development by some paper emulsions. It is not a good idea to use it. When used in a film developer, it is usually used at the milligram level.

It is very very reactive and a powerful inhibitor. Take care if you do use it.

PE

dancqu said:

Although I've not kept exact records, testing
paper developers with no bromide included
has lead me to conclude that some papers
do not need a bromided developer. Also,
some may need more than others. Dan

Click to expand...

I mix up D-72 from bulk chems without any bromide, and it seems to work fine with Ilford MG IV FB. I haven't noticed any fogging or contrast issues.

Wait! I am sorry. I should have mentioned that this is for a film developer. In particular the Microphen-like developer:

Water(50C) - 750ml
Sodium Sulfite - 100g
Hydroquinone - 5g
Borax - 3g
Boric Acid - 3.5g
Potassium bromide - 1g
Phenidone - 0.2g
Water to make 1000ml

I mixed 4x this volume (with 4x the ingredients of course) with 20 ml of 0.001% of potassium iodide restrainer yesterday and tried a test roll. The film was developed for 6 minutes. Awful fog similar to stand development for one hour. Obviously not enough restrainer.

Thanks!

desertrat said:

I mix up D-72 from bulk chems without any bromide, and it seems to work fine with Ilford MG IV FB. I haven't noticed any fogging or contrast issues.

Click to expand...

It strongly depends on what paper you use.

PE

strangepics said:

Wait! I am sorry. I should have mentioned that this is for a film developer. In particular the Microphen-like developer:

Water(50C) - 750ml
Sodium Sulfite - 100g
Hydroquinone - 5g
Borax - 3g
Boric Acid - 3.5g
Potassium bromide - 1g
Phenidone - 0.2g
Water to make 1000ml

I mixed 4x this volume (with 4x the ingredients of course) with 20 ml of 0.001% of potassium iodide restrainer yesterday and tried a test roll. The film was developed for 6 minutes. Awful fog similar to stand development for one hour. Obviously not enough restrainer.

Thanks!

Click to expand...

This is not a Microphen type developer.

It's a PQ derivative of ID-11/D76. The new edition of Anchells Cookbook will have the correction. ID-68 is the Microphen type developer. In 1954 Ilford published some suggested formulae for Phenidone developers, Phenidone had only been commercially available for about 18 months. There are at least 3 variations of this PQ - ID-11 type developer published, before the final re-formulation as ID-68.

You could add 20 to 30 gms Sodium Cloride per litre to the working soluton. This is similar to a recommendation Ilford made in a technical sheet P10 in 1965. This should give extremely fine grain, compared to ID-11/D76, with about a stop speed loss.

Ian